Your skill will accomplish what the force of many cannot 

PerlMonks 
Comment onby gods 
on Feb 11, 2000 at 00:06 UTC ( #3333=superdoc: print w/replies, xml )  Need Help?? 
Hi all I'm trying to build a calculator that would accept mathematical expressions from different users. I'm stuck in one part and would like to know good ways of solving the following problem: I need to check what user enters against my answer. Say I have x + 1 as a correct answer, but user entered 1 + x. How can I build something that would check for all associativity and commutativity in a given equation? Of course that's one example but the problem gets more complicated when you have more than 4 variables. (with one unknown variable things are easy just easy) I have used shunting yard algorithm to find the operatorsprecedence but it complicated things and I failed to do the task. Any idea how would I solve such a problem? In reply to List all different equations for a given one by jess195

